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Comment by 9rx

21 hours ago

> Well, then they look awkward and have give a feel like it's a syntax abuse.

So nothing to worry about?

> how do I insert an element in the middle of an array?

Same as in C. If the array allocation is large enough, you can move the right hand side to the next memory location, and then replace the middle value.

Something like:

    replaceWith := 3
    replaceAt := 2
    array := [5]int{1, 2, 4, 5}
    size := 4
    for i := size; i > replaceAt; i-- {
        array[i] = array[i-1]
    }
    array[replaceAt] = replaceWith
    fmt.Println(array) // Output: [1 2 3 4 5]

If the array is not large enough, well, you are out of luck. Just like C, arrays must be allocated with a fixed size defined at compile time.

> The docs on the internet suggest that slices in go are exactly like in Rust, a contiguous sequence of array's elements.

They're exactly like how you'd implement a slice in C:

    struct slice {
        void *ptr;
        size_t len;
        size_t cap;
    };

The only thing Go really adds, aside from making slice a built-in type, that you wouldn't find in C is the [:] syntax.

Which isn't exactly the same as Rust. Technically, a Rust slice looks something like:

    struct slice {
        void *ptr;
        size_t len;
    };

There is some obvious overlap, of course. It still has to run on the same computer at the end of the day. But there is enough magic in Rust to hide the details that I think that you lose the nuance in that description. Go, on the other hand, picks up the exact same patterns one uses in C. So if you understand how you'd do it in C, you understand how you'd do it in Go.

Of course, that does mean operating a bit lower level than some developers are used to. Go favours making expensive operations obvious so that is a tradeoff it is willing to make, but regardless if it were to make it more familiar to developers coming from the land of magic it stands that it would require more magic, not less.

Ok, so mostly we agree. And I was right that you can't just concatenate different slices (e.g. to remove one item from the middle), hence Go has to do a lot of work under the hood to do that. I count this as magic.

  • > Ok, so mostly we agree.

    I don't follow. Information isn't agreeable or disagreeable, it just is.

    > And I was right that you can't just concatenate different slices

    That's right. You would have to physically move the capacitors in your RAM around (while remaining powered!) in order to do that. Given the limits of our current understanding of science, that's impossible.

    > hence Go has to do a lot of work under the hood to do that.

    Do what? You can't actually do that. It cannot be done at the hardware level. There is nothing a programming language can do to enable it.

    All a programming language can do is what we earlier demonstrated for arrays, or as slices allow dynamic allocation, if the original slice is not large enough you can also copy smaller slices into a new slice using a similar technique to the for loop above.

    Go does offer a copy function and an append function that do the same kind of thing as the for loop above so you do not have to write the loop yourself every time. I guess that's what you think is magic? If you are suggesting that calling a function is magic, well, uh... You're not going to like this whole modern programming thing. Even Rust has functions, I'm afraid.

    The Go standard library also provides a function for inserting into the middle of a slice, but, again, that's just a plain old boring function that adds some conditional logic around the use of the append and copy functions. It is really no different to how you'd write the code yourself. So, unless function are still deemed magic...

  • I may have misunderstood "you can't just concatenate different slices (e.g. to remove one item from the middle" but does [0] not do what you're talking about?

    (with the caveat that anything else sharing `a` will be mangled, obvs.)

    [0] https://go.dev/play/p/uQdoa3mUF00